To answers all the questions about our fecal bacteria monitoring program you never knew you had!
Where do we monitor?
We monitor on seven sites on the Willett Branch and Little Falls Branch. These creeks run through Bethesda and Chevy Chase - the Willett Branch starting in downtown Bethesda, and the Little Falls starting in the Chevy Chase Club in Chevy Chase. A map of our testing locations is HERE.
what are the goals of our program and what did we learn?
There are two goals for our program - first is to inform residents of whether the creek is safe to play in. Fecal bacteria levels over 410 MPM do not meet the MD state standards for safe water play and in general, the creeks are NOT meeting the standard. A second goal is to see if the repairs that WSSC made in the last decade on leaking pipes are doing their job. Our tests suggests that they are - the levels up and downstream from the repairs are not significantly different. However, all the streams have very high levels of fecal bacteria.
how did we pick our testing locations?
Given the goals of our program, we picked sites with two criteria - 1) places with easy access to the creek and known recreation areas and 2) sites that were upstream and downstream from known leakages.
why so many sites on such short streams?
Why do we test so many spots on such short creeks? While creeks get their baseline water from groundwater, all the area storm drains dump into the creeks too. All along the creek banks are outlet pipes, so when it rains, different sections of the creek get storm water run-off from different parts of the neighborhood. And depending on what is in the storm drain system at any given time, we could see a wide variation in fecal bacteria levels even in small stretches of the creek.
For example - our testing site at the Willard Avenue Neighborhood Park is less than 1/2 mile downstream from the Somerset site, yet this site failed on Week 5, and the Somerset site passed. There is a major outlet from the Jenifer Run between the two sites that could be causing the higher downstream count. So, while splashing in the Somerset section was safe, residents were warned to stay out of the area by the Willard Avenue Neighborhood Park. Fortunately, as a local watershed group, we are able to do this type of hyper local testing!
Why are the fecal bacteria levels so high?
That's a hard question. In Montgomery County, where the creeks begin, there is a separate sewer and storm water waste system. That means that the source of the fecal matter should not be human unless the sewer system is leaking into the creek or waste water pipes are incorrectly plumbed and the wastewater is being sent to the storm drain system instead of the sewer treatment plants. Both are known problems and in the past decade, WSSC has addressed broken sewer pipes and incorrectly plumbed wastewater in several locations in the watershed. For the really high numbers (over 4.000), we suspect that human waste contributes a lot. DNA testing on the Willett Branch has confirmed this suspicion and WSSC and MoCoDEP is following up by investigating the problem.
For the smaller, but still high numbers (in the 1,000 range), we don't know and no one is investigating the problem. The party line is that it's dog poop - but we don't see how that is possible. That's a lot of dog waste. However, after a big rain, all the surface dog waste along with wildlife waste wash into the creek, so there is that.
What is going on with Willett Branch?
For the very high numbers in the Willett Branch, LFWA did DNA testing on the samples last fall and determined that the fecal bacteria source was human. WSSC agreed with us and the Montgomery County Department of Environment Protection has hired contractors to figure out what is happening. Unfortunately, this takes a long time. We got an update in March that they were still working on it. And in July, we got another update that said they were still working on it. We'll let people know when we hear. MoCo DEP has also set up a webpage to address questions. https://www.montgomerycountymd.gov/water/streams/bacteria.html It doesn't have a lot of information, but it's a start. They said they would update the page when they had more information.
Why do the levels go up after it rains?
We can’t really explain it from a data based view - no one has done that sort of analysis as far as our research can find. And our numbers don’t 100% correlate. There is a correlation when there is a combined system - stormwater and wastewater together in the same pipes to the water treatment plant. (Combined Sewer Overflows is the proper name - CSO) When it rains, the stormwater run-off, overwhelms the system and it spills out into creeks. It's designed to do that! But, while they have a CSO system in DC, in Montgomery County where our creeks are we have a separate sewer and stormwater system. In a perfect world, the sewer system and the storm drain system never interact. However, if the sewer system leaks, it could run into the creek especially if there was a storm to wash the waste. There is a manhole quite near the Little Falls Branch in Somerset which is known to leak from time to time. So, when it rains, the run-off carries the waste right into the creek.
As for other reasons that the numbers go up after a big storm, the most common explanation is that the storm washes all the fecal wastes into the storm drain system which outlets into the creek. Walk along any creek and you'll see the conduit pipes. That's the storm drain outlets. So, anything on the surface gets washed in. DNA testing done by WSSC gave the types of waste by percentage. You can see the percentages HERE.
Has WSSC ever done DNA testing?
In 2009-2012, by Court decree, as a result of a suit brought by several environmental groups charging that the sewers were leaking, WSSC did DNA testing and found high levels of human fecal matter as well as fecal matter from dogs, deer, birds and other wildlife. They discovered lots of leaks and spent a good many years relining the sewer pipes and fixing the leaks. You can see the results of their tests on our website at https://www.lfwa.org/fecal-monitoring-results They used different testing because of the DNA part, so you can't compare the numbers to our numbers, but all the sites failed by the standards they used.
One thing we did early in our program was test above and below the sites where WSSC "fixed" the leaks. We found no difference in the fecal bacteria, so while the numbers were high, it does look like the leaks were fixed. So that was good news!
What other streams in the area are tested?
The Anacostia Riverkeeper and the Potomac Riverkeepers have testing programs too. You can see their results for other locations in the DMV at https://www.theswimguide.org It has "beaches" all over the world, - zoom in on the map to find sites that interest you.